Abstract: Traditional approaches to molecularly imprinted polymer (MIP) design and optimisation typically afford a template (T) : functional monomer (FM) : crosslinker (CL) ratio of 1 : 2 : 20 to 1 : 4 : 20. This approach for 1,2,3-trichlorobenzene (7) as template gave a styrene based MIP (MIPSTY) with an imprinting factor (IF) = 1.3. An extreme vertices mixture design (EVMD) approach was applied, and in two design cycles, 15 total experimental points, the optimum composition for MIPSTY was determined as 0.40 : 0.05 : 0.55 (T : FM : CL) with IF = 2.8. Refinements gave optimum T : FM : CL ratios for the functional monomers: 4-vinylpyridine (4VP, 0.40 : 0.02 : 0.58); 2,4,6-trimethylstyrene (TMS, 0.40 : 0.02 : 0.58) and 2,3,4,5,6-pentafluorostyrene (PFS, 0.30 : 0.12 : 0.58) with IF = 2.8, 2.8 and 3.7 respectively. These ratios deviated significantly from the traditional MIP synthesis ratio. The low levels of FM for all MIPs, except for MIPPFS, suggest that imprinting was more consistent with T-CL, than FM-T, interactions. Analysis of the specific interactions and removal (SR) of 7 with these MIPs revealed that the SR with MIPSTY increased from 36% at 0.02 STY to 48% at 0.13 STY; with MIPTMS SR increased from 38% at 0.02 TMS to 42% at 0.10 TMS; and with MIPPFS SR increased from 34% at 0.02 PFS to 56% at 0.14 PFS. MIP4VP saw a decline in SR with increasing FM, with the highest SR was 35% at 0.02 4VP. This is consistent with changes in the non-specific interactions between 7 and the MIPs. Increasing the proportion of PFS produced the largest increase in imprinting of 7 demonstrated by the highest SR (56%) and highest IF (3.7). The application of an EVMD approach resulted in the IF of MIPSTY increased from 1.3 to 2.8. The highest IF achieved by this study was 3.7 for MIPPFS in proportions of 0.30 : 0.12 : 0.48 (T : FM : CL)Template and target information:1,2,3-trichlorobenzene